Effects of substituting P2O5 for B2O3 on the thermal and optical properties of sodium borophosphate glasses doped with Er

Abstract In this paper a set of (95-x) P 2 O 5 –xB 2 O 3 –4.9Na 2 O–0.1Er 2 O 3 (x = 5–10–15–20 mol%) samples was prepared using a conventional melt-quenching technique. A glass ceramic phase was confirmed by X-ray diffraction. Small crystallites at the B 2 O 3 addition were detected by Raman scattering. The glass containing 20 mol% B 2 O 3 shows a high thermal stability with a value ΔT = T c –T g exceeding 100 °C, where T g and T c are the glass transition and crystallization onset temperatures. The Raman spectroscopy measurement shows that B O P bonds were present in the glasses. From the absorption edge studies, the value of the optical band gap E opt has been evaluated. The decrease in optical band gap values and consequently the decrease in Urbach's energies confirm the less extension of the localized states within the band gap. As a result, there shall be an increase in the order of the glass network. The variation in optical parameters is owing to the substitution of B 2 O 3 oxides in P 2 O 5 –Na 2 O–Er 2 O 3 glass network. The fundamental absorption edge for all the glasses was analyzed and the Judd–Ofelt parameters (Ω 2 , Ω 4 and Ω 6 ) were obtained. The PL intensity, the PL life time and the quantum efficiency relative to the 4 I 13/2 → 4 I 15/2 (1530 nm) transition of Er 3 + were all found to decrease with the addition of B 2 O 3 .